Medium supply apparatus

ABSTRACT

A medium supply apparatus supplying a rolled medium includes a tension member contacts to the medium to apply a tension to the medium, a state switching part that switches states of the tension member between first and second states, and a control unit. The tension member is swingable between a first position at which a first corner angle (θ1) and a second position at which a second corner angle (θ2) is formed, the second corner angle (θ2) being greater than the first corner angle (θ1). The control unit causes the state switching part to switch the state of the tension member to the fixed state in the first position when the medium is supplied, the control unit causes the state switching part to switch the state of the tension member to the releasing state in the first position when the control unit does not receive an image forming start signal for a predetermined period, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the second position.

TECHNICAL FIELD

The present invention relates to a medium supply apparatus for supplying a medium which is wound into a roll shape.

BACKGROUND

A printer featuring a roll sheet guide member provided has been proposed (see patent number 1). In the printer, the roll sheet guide member guides the roll sheet to a roller, the roll sheet being pulled from a roll sheet support part. When performing a printing, the roll sheet guide member is advanced by a driving unit to a advancing position at which a roll sheet path is bent so that the roll sheet comes to contact with the roller for a predetermined length. When not performing the printing, the roller paper guide member is retrieved by the driving unit to a releasing position at which the roller paper is released. In the printer in patent document 1, the roller paper is prevented from having a curved habit (a curved portion) by retrieving the roll sheet guide member when not printing.

RELATED ART

[Patent Document 1]

JP Laid Open Patent Publication H10-297043 (e.g., paragraphs 0012-paragraph 0019, FIG. 2)

It is noted that, in the specification, a “retracted position” and a “releasing position” of a tension roller are used for a similar meaning in correspondence with contexts.

However, according to the technique of Patent Document 1, the roll sheet guide member is merely retrieved to the releasing position for releasing the roll sheet, and the roll sheet passed between the roll sheet support part and the roller is held while being curved. It is impossible to avoid that the roll sheet is curved.

The present invention is made to solve the above-described drawback. It aims to provide a medium supply apparatus capable of avoiding a curved habit that affects transportation of a medium wound in a roll shape.

SUMMARY

A medium supply apparatus, disclosed in the application, includes a holder that is configured to rotatably support a medium, which is wound in a rolled shape and to be rotated by a drive part, a conveyance part that conveys the medium in a conveyance direction, and is disposed in a downstream side with respect to the holder in the conveyance direction, a tension member that is disposed between the holder and the conveyance part, and contacts to the medium, which is positioned between the holder and the conveyance part, to apply a tension to the medium, a state switching part that has a detection sensor that detects a position of the tension member and switches states of the tension member between two states in correspondence with a detection result by the detection sensor, one state being a fixed state where the tension member is locked such that the tension member is not movable, and the other state being releasing state where the tension members is not locked such that the tension member is movable, a control unit that controls the drive part for the holder, conveyance part, and the state switching part, wherein the tension member is swingable between a first position at which a first corner angle (θ1) is formed and a second position at which a second corner angle (θ2) is formed, the first and second corner angles being determined with two tangent lines formed on the tension member which are seen from a rotational axis view of the holder, one tangent line being at an upstream contact point (UCP) where the medium comes in first contact with the tension member, and the other tangent line being at a downstream contact point (DCP) where the medium, which curves around an outer peripheral of the tension member, departs from the outer peripheral of the tension member, the second corner angle (θ2) being greater than the first corner angle (θ1), the control unit causes the state switching part to switch the state of the tension member to the fixed state in the first position when the medium is supplied, and the control unit causes the state switching part to switch the state of the tension member to the releasing state in the first position when the control unit does not receive an image forming start signal, which is a signal to start an image forming process, for a predetermined period after the conveyance part stops conveying the medium so that the tension medium is moved to the second position as the drive part drives the holder to rotate in an opposite direction to the conveyance direction, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the second position.

Also, another medium supply apparatus, which is disclosed in the application, includes a holder that is configured to rotatably support a medium, which is wound in a rolled shape and to be rotated by a drive part, a conveyance part that conveys the medium in a conveyance direction, and is disposed in a downstream side with respect to the holder in the conveyance direction, a medium guide part that has a curved portion, is disposed in a upstream side with the conveyance part in the conveyance direction, a tension member that is disposed between the holder and the medium guide part along the conveyance path and applies a tension to the medium by contacting, the tension member being swingable between a first position and a second position, when the tension member is at the first position, the medium being curved by the curved portion of the medium guide part so that the medium is in a curved shape, seen from a side view of the medium being conveyed, the side view being perpendicular to the conveyance direction and to flat surfaces of the medium, when the tension member is at the second position, the medium not contacting to the curved portion of the medium guide part so that the medium is in a linear shape, seen from the side view of the medium, the tension applied by the tension member being oriented from the second position to the first position, a state switching part that has a detection sensor that detects a position of the tension member and switches states of the tension member between two states in correspondence with a detection result by the detection sensor, one state being a fixed state where the tension member is locked such that the tension member is not movable, and the other state being releasing state where the tension members is not locked such that the tension member is movable, a control unit that controls the drive part for the holder, conveyance part, and the state switching part, wherein the control unit causes the state switching part to switch the state of the tension member to the fixed state in the first position when the medium is conveyed to the downstream side for an image forming process, and the control unit causes the state switching part to switch the state of the tension member to the releasing state in the first position when the control unit does not receive print data for the image forming process for a predetermined period after the conveyance part stops conveying the medium so that the tension medium is moved to the second position as the drive part drives the holder to rotate in an opposite direction to the conveyance direction, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the second position.

According to the present invention, it is possible to prevent the curved habit of the medium wound into the roll shape, which affects the transportation.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a schematic configuration of the roll sheet supply apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a control system of the roll sheet supply apparatus according to the embodiment.

FIG. 3A to FIG. 3C are diagrams for explaining the operations of the roll sheet supply apparatus according to the embodiment.

FIG. 4A to FIG. 4C are diagrams for explaining the operations of the roll sheet supply apparatus according to the embodiment, sequential operations shown in FIG. 3A to FIG. 3C.

FIG. 5A to FIG. 5C are diagrams for explaining the operations of the roll sheet supply apparatus according to the embodiment, sequential operations shown in FIG. 4A to FIG. 4C.

FIG. 6 is a flowchart showing a series of operations of the roll sheet supply apparatus according to the embodiment.

FIG. 7 is a flowchart showing a series of operations of the roll sheet supply apparatus according to the embodiment, sequential operations following step S10 in FIG. 6.

FIG. 8 is a flowchart showing a series of operations of the roll sheet supply apparatus according to the embodiment, sequential operations following step S21 in FIG. 7

FIG. 9A shows an enlarged, simplified view of a first corner angle (θ1) where the tension member is in the first position. FIG. 9B shows an enlarged, simplified view of a second corner angle (θ2) where the tension member is in the second position.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS Embodiments <<1>> Configuration

FIG. 1 is a cross-sectional view showing a schematic configuration of a roll sheet supply device 100 as a medium supply apparatus according to an embodiment of the present invention. Hereinafter, the roll sheet supply device 100 according to the embodiment will be described from the upstream side in the transport direction E of roll sheet (continuous sheet). In FIG. 1, the conveying direction E of roll sheet (continuous sheet) is indicated by arrows. In FIG. 1, the upstream side in the conveying direction E is the right side in the drawing, and the downstream side in the conveying direction E is the left side.

The roll sheet supply device 100 according to the embodiment feeds a continuous sheet 101 a from the roll sheet 101 formed of the continuous sheet (medium) 101 a, which is wound in a roll form, and supplies the continuous sheet 101 a to the printing device 200, which is an external apparatus. Note that the printing device 200 is an example of the external apparatus, and that the external apparatus is not limited to the printing device 200. In the present application, the roll sheet 101 is configured with a portion wound in a roll form and a portion drawn out from the wound portion in the roll form. The drawn portion is referred to as the “continuous sheet 101 a.”

FIG. 1 illustrates the roll sheet supply device 100 that is connected to the printing device 200 receiving a supply of the roll sheet 101. The roll sheet supply device 100 is connected to the printing device 200 by being inserted in the mounting part of the printing device 200, for example. Note that the structure for connecting the roll sheet supply device 100 and the printing device 200 varies as long as the continuous sheet 101 a supplied from the roll sheet supply device 100 is conveyed to a printing position of the printing device 200.

As shown in FIG. 1, the roll sheet supply device 100 includes a roll sheet holder 10 as a holder for rotatably supporting the roll sheet 101, a tension roller part 20 serving as a tension member, and a conveyance roller 40 serving as a conveyance part for conveying the continuous sheet 101 a in the conveyance direction E. The tension roller part 20 is disposed between the roll sheet holder 10 and the conveyance roller 40, and provides a tension to the continuous sheet 101 a by abutting on the continuous sheet 101, which is positioned between the roll sheet holder 10 and the conveyance roller 40. The roll sheet supply device 100 may include an upper sensor 31 and a lower sensor 32 serving as position sensors for detecting the position of the tension roller part 20, a sheet sensor 33, a sheet end sensor 34, a holder rotation sensor 35, a cutter unit 50, and a supply roller 60.

As shown in FIG. 1, at the roll sheet supply device 100, the roll sheet 101 is set in a rotatable state in the roll sheet holder 10. The roll sheet 101 is configured, for example, by a web medium being wound on a roll core 102 in the roll form.

The roll sheet holder 10 rotates clockwise or counter-clockwise by a rotational driving force generated by a holder drive motor 117 as a driving part. The Roll sheet holder 10 feeds the continuous sheet 101 a from the roll sheet 101 which is supported on the roll sheet holder 10 by rotating counterclockwise, which is the first direction in FIG. 1.

Further, the roll sheet holder 10, in a state where the leading end 101 b of the fed continuous sheet 101 a is sandwiched by the conveyance rollers 40, rotates such that the continuous sheet 101 a is wound to the rearward (or opposite direction of the conveyance direction E of the continuous sheet 101 a), and pulls the continuous sheet 101 a rearwardly, and operates so as to provide a tension (hereinafter referred to as “back tension”) to the continuous sheet 101 a. The roll sheet holder 10 rewinds the continuous sheet 101 a by rotating in the clockwise direction which is the second direction in FIG. 1.

When applying the back tension against the continuous sheet 101 a, for example, it is preferred not to apply a load, which is the predetermined upper limit value or more (pulling force), to the continuous sheet 101 a by a mechanical torque limiter. Further, it is preferred that the upper limit value set in the torque limiter is equal to or larger than the self weight of the tension roller part 20.

As shown in FIG. 1, at the upper portion of the roll sheet holder 10, a holder rotation sensor 35 for detecting the rotation of the roll sheet holder 10 is provided. The holder rotation sensor 35 detects the rotation of the roll sheet holder 10 by detecting slits which rotates together with the roll sheet holder 10.

As shown in FIG. 1, at the downstream of the conveyance direction E of the roll sheet holder 10, a tension roller part 20 is provided. The tension roller part 20 is a means to apply a predetermined tension to the continuous sheet 101 a by contacting the continuous sheet 101 a fed from the roll sheet holder 10. By the tension roller part 20 applying the predetermined tension to the continuous sheet 101 a, it is possible to enhance a conveyance accuracy of the continuous sheet 101 a (or to realize a stable conveyance).

A sheet guide part 401 (or medium guide part) is disposed between the tension roller 25 and the conveyance roller 40 (or nipping point NP) on the medium conveyance path. The sheet guide part has a curved portion along which the sheet is curved and held in the curved shape while the tension roller 25 stays at a first position discussed below. With the structure, a certain tension provided by the tension roller to the sheet is maintained between the conveyance roller and the tension roller in order to enhance the conveyance accuracy. In other words, a steady conveyance of sheet is achieved.

As shown in FIG. 1, the tension roller part 20 includes a tension roller support shaft 21, a bar 22, a bar 23, a spring 24, and a roller 25. The tension roller part 20 is able to rotate at a predetermined angle around the tension roller support shaft 21. The tension roller part 20 includes a roller 25 as a contact part which abuts against the continuous sheet 101 a between the roll sheet 101 supported by the roll sheet holder 10 and the conveyance roller 40 as a conveyance part, and is movable between following first and second positions by a rotation of the tension roller part 20. The first position (the position shown in FIG. 1) is distant away from the conveyance roller 40. The second position (the position shown in FIG. 4 (c) which will be described later) is close to the conveyance roller 40. FIG. 1 shows a state in which the roller 25 of the tension roller part 20 is in the first position away from the conveyance roller 40. More specifically, in FIG. 1, assuming an imaginary linear line connecting DP and NP, the first position is farther to the imaginary linear line than the second position.

When the tension roller is positioned at the first position, the sheet, which is between the nipping portion and the tension roller, is in contact with the curved portion of the sheet guide part 401 such that the sheet is curved along the sheet guide part 401. On the other hand, when the tension roller is positioned at the second position, the sheet, which is between the nipping portion and the tension roller, is not in contact with the curved portion of the sheet guide part 401. The sheet between them has a linear shape in the side view. The linear shape of the sheet is illustrated in FIG. 4C. At the second position of the tension roller, the roller may contact to the sheet or may not contact to the sheet. In a case where the tension roller contacts to the sheet at the second position, the sheet is guided with the tension roller as well as the sheet guide part.

At the tension roller shaft 21, a solenoid 119 is provided to hold or release the position of the tension roller part 20 (fixed) (shown in FIG. 2 to be described later). The tension roller support shaft 21 is switched between a fixed state for restricting the movement of the tension roller part 20 and a released state for allowing the tension roller part 20 to move by controlling the energization of the solenoid 119. The solenoid 119 and the solenoid drive driver 115 constitute a state switching part for switching the tension roller part 20 to either at the fixed state or at the released state. When the solenoid 119 is energized (or electrically powered), the position of the tension roller part 20 is released. On the other hand, when the energization to the solenoid 119 is interrupted (or shut down), the position of the tension roller part 20 is held (fixed).

The bar 22 is fixed to the tension roller support shaft 21. The bar 22 is provided with the spring 24, and the bar 22 is connected to the bar 23 as a support member via the spring 24. At one end of the bar 23, the roller 25 as a contact part is rotatably provided with respect to the bar 23. The continuous sheet 101 a contacts to the lower portion of the roller 25. The roller 25 is driven to rotate in correspondence with the conveyance of the continuous sheet 101 a.

As shown in FIG. 1, a tension is always applied in the direction of the arrow in the figure to the continuous sheet 101 a that is in contact with the lower portion of the roller 25 by the force of the spring 24. As a result, a frictional force is generated between the continuous sheet 101 a and the roller 25, and the conveyance accuracy of the continuous sheet 101 a is improved. The continuous sheet 101 a that is in contact with the roller 25 has a first corner angle θ1 at the contact portion with the roller 25. The first corner angle θ1 is smaller than the second corner angle θ2 as shown in FIG. 4(c), which is described later.

As shown in FIG. 1, above or below the tension roller support shaft 21, the upper sensor 31 as a second position sensor for detecting the position of the tension roller part 20 and the lower sensor 32 the first position sensor are provided. The upper sensor 31 and the lower sensor 32 are sensors for detecting the positions of the tension roller part 20. The upper sensor 31 detects the second position of the tension roller part 20. The lower sensor 32 detects the first position of the tension roller part 20. The output states of the sensors 31 and 32 (for example, a detection signal including a detection state and a non-detection state) are monitored, the solenoid 119 provided with the tension roller support shaft 21 is controlled with respect to its energization based on these output states.

As shown in FIG. 1, the conveyance roller 40 is provided on the downstream side of the conveyance direction E with respect to the tension roller part 20. The conveyance roller 40 is a conveying means for conveying the continuous sheet 101 a toward the printing device 200 in which the roll sheet supply device 100 is equipped. The conveyance roller 40 is connected to a roller drive motor 118 (shown in FIG. 2 to be described later) via a drive force transmission mechanism such as gears, and is configured to be rotatable. The conveyance roller 40 draws the continuous sheet 101 a from the roll sheet 101 set in the roll sheet holder 10 and conveys the drawn out continuous sheet 101 a toward the cutter unit 50.

As shown in FIG. 1, the cutter unit 50 is provided on the downstream side of the conveying direction E with respect to the conveyance roller 40. The cutter unit 50 cuts the continuous sheet 101 a passing through the cutter unit 50 and separates a portion that is on the leading end 101 b side of the continuous sheet 101 a from the continuous sheet 101 a drawn from the roll sheet 101. The cutter unit 50 cuts the continuous sheet 101 a when the passed continuous sheet 101 a reaches the printing length that corresponds to the print data.

As shown in FIG. 1, the supply roller 60 is provided on the downstream side of the conveying direction E with respect to the cutter unit 50. The supply roller 60 is a conveying means for conveying the continuous sheet 101 a toward the printing device 200. The supply roller 60 is connected to the roller drive motor 118 via a driving force transmission mechanism such as gears and configured to be rotatable. The supply roller 60 conveys the continuous sheet 101 a that is cut into a predetermined length by the cutter unit 50 toward the printing device 200.

As shown in FIG. 1, the sheet sensor 33 is provided on the upstream side of the conveying direction E with respect to the conveyance roller 40. When the operator sets the leading end 101 b of the continuous sheet 101 a at the sheet setting position 33 a, the sheet sensor 33 detects the presence or absence of paper (or continuous sheet 101 a) at the sheet setting position 33 a on the upstream side of the conveying direction E with respect to the conveyance roller 40.

As shown in FIG. 1, the sheet end sensor 34 is provided downstream of the conveying direction E of the conveyance roller 40. The sheet end sensor 34 is a sensor that detects the cueing of the paper (continuous sheet 101 a) at the sheet standby position 34 a on the downstream side of the conveying direction E with respect to the conveyance roller 40 (that is, detects the presence or absence of the leading end 101 b).

FIG. 2 is a block diagram showing a schematic configuration of a control system of the roll sheet supply device 100 according to the embodiment. As shown in FIG. 2, the control unit 107 of the roll sheet supply device 100 includes a CPU (Central Processing Unit) 108, a ROM (Read Only Memory) 110, and a RAM (Random Access Memory) 111. As shown in FIG. 2, the CPU 108 is connected to the ROM 110, the RAM 111, and the IO port (Input Output Port) 112 with the CPU bus 109.

As shown in FIG. 2, the control unit 107 is connected to the holder drive motor driver 113 for driving the holder drive motor 117 via the IO port 112. In addition, the control unit 107 is connected to a roller drive motor driver 114 for driving the roller drive motor 118 via the IO port 112. In addition, the control unit 107 is connected to a solenoid driving driver 115 for driving the solenoid 119 via the IO port 112. Further, the control unit 107 is connected to a cutter unit drive driver 116 for driving the cutter unit 50 via the IO port 112. Operations of the holder drive motor 117, the roller drive motor 118, the solenoid 119, and the cutter unit 50 are controlled by the control unit 107.

As shown in FIG. 2, the control unit 107 is connected to a lower sensor 32 and to an upper sensor 31 via the IO port 112, and is able to detect the position of the tension roller part 20. Further, the control unit 107 is connected to the sheet sensor 33 via the IO port 112.

As shown in FIG. 2, the control unit 107 is connected to the sheet end sensor 34 on the downstream side with respect to the conveyance roller 40 via the IO port 112. Further, the control unit 107 is connected to the holder rotation sensor 35 and can detect the rotation of the roll sheet holder 10.

As shown in FIG. 2, the control unit 107 is connected to the interface circuit 120 via the IO port 112. The interface circuit 120 is connected to the print part 201 of the printing device 200 via the interface cable 121.

<<2>> Operations

FIG. 3A to FIG. 3C are diagrams for explaining the operations of the roll sheet supply device 100 according to the embodiment. It is noted that descriptions of the printing device 200 are omitted in FIG. 3A to FIG. 3C.

As shown in FIG. 3A, in order to set the continuous sheet 101 a at a predetermined position, the operator first pulls the continuous sheet 101 a from the roll sheet 101, passed it under the tension roller part 20, and sets it on the conveyance roller 40.

As shown in FIG. 3B, when the sheet sensor 33 detects the leading end 101 b of the continuous sheet 101 a, the holder drive motor 117 is driven to start conveying the continuous sheet 101 a. When the sheet end sensor 34 detects the presence of sheet, the continuous sheet 101 a is conveyed by a preset predetermined distance, and the rotation of the holder drive motor 117 stops.

As shown in FIG. 3C, in order to apply tension by the tension roller part 20 against the continuous sheet 101 a that is drawn too much by the operator when setting the continuous sheet 101 a, the roll sheet holder 10 connected to the holder drive motor 117 is rotated in the back feed direction (BFD), and the continuous sheet 101 a is wound up so that a slack portion of the continuous sheet 101 a is eliminated.

FIG. 4A to FIG. 4C are diagrams for explaining the operations of the roll sheet supply device 100 according to the embodiment, showing the operations following the operations shown in FIG. 3A to FIG. 3C. It is noted that the description of the printing device 200 is omitted in FIG. 4A to FIG. 4C.

As shown in FIG. 4 (a), when the output state of the holder rotation sensor 35 has not been changed, it is determined that the winding of the slack portion of the continuous sheet 101 a is completed, the control unit stops the rotation of the holder drive motor 117. At this time, the electric power to the solenoid 119 (or energization of the solenoid) is interrupted, and the position of the tension roller part 20 is held (Lock state). At this time, a tension is given to the continuous sheet 101 a by the tension roller part 20, and a tension is applied to the continuous sheet 101 a that is between the conveyance roller 40 and the roll sheet holder 10.

As shown in FIG. 4 (b), when the print data has been received within a set time (or predetermined period), the roll sheet supply device 100 determines that it is now in the supply period of the roll sheet 101, conveys the continuous sheet 101 a to the printing device 200. The printing device 200 performs printing. At the time of printing, by rotating the roll sheet holder 10 connected to the holder drive motor 117 in the back feed direction (or clockwise arrow direction shown in the roll sheet holder 10 in FIG. 4B (b)), unnecessary feeding of the continuous sheet 101 a is prevented, which is caused by the conveying of the conveyance roller 40, the supply roller 60, and a conveying mechanism inside the printing device 200. Such print data is a signal that starts executing an image forming process. The signal may be called an image forming start signal.

As shown in FIG. 4C, when print data are not received within the set time, the roll sheet supply device 100 enters the supply stop period of the roll sheet 101, electrically powers the solenoid 119 that is provided with the tension roller support shaft 21, and releases the lock, and the tension roller section 20 is released so as to be able to rotate up and down. Then, in order to move the tension roller part 20 to the highest position which is the retracted position at the time of non-printing, the roll sheet holder 10 connected to the holder drive motor 117 is rotated in the back feed direction, and the continuous sheet 101 a is wound up. At this time, the tension roller part 20 is in the second position that is close to the conveyance roller 40. Being The first position of the tension roller part means a state where the medium is being conveyed, and the continuous sheet 101 a is being styled along the roller 25 and the sheet guide part 401 and able to be conveyed while maintaining the conveyance accuracy. Being the second position of the tension roller part manes another state where the styling of the continuous sheet 101 a is released (or a state where the sheet does not contact to the sheet guide part). In other words, that is a state where the sheet is nipped only with the conveyance roller and the roller 25. In the state, since a back tension is applied to the roll sheet holder 10, the sheet is basically in a linear state, as seen in FIG. 4C. Here, the length (medium length) of the continuous sheet 101 a that is determined by between the roll sheet holder 10 and the conveyance roller 40 in the case where the tension roller part 20 is in the first position (see FIG. 1) is longer than the length (medium length) of the continuous sheet 101 a that is determined by between the roll sheet holder 10 and the conveyance roller 40 in the case where the tension roller part 20 is in the second position. The second position of the tension roller section 20 is desirably a position at which the length of the continuous sheet 101 a determined by between the roll sheet holder 10 and the conveyance roller 40 is minimized.

Here, the medium lengths between the roll sheet holder 10 and conveyance roller 40 are more specifically defined by lengths along the conveyance path starting at departing point DP on the roll sheet up to nipping point NP on the conveyance roller 40. The departing point DP is a surface point of the roll sheet where a conveyed continuous sheet departs from the remaining roll sheet, see DPs in FIG. 1 and FIG. 4C. The nipping point is a surface point of the conveyance roller where the roller contacts to the continuous sheet 101 a first. The medium lengths between point DP and point NP may be defined as conveyance lengths.

The tension roller part 20 is detected with the upper sensor 31 when reaching the second position.

When the roll sheet holder 10 is rotated in the back feed direction, which is opposite to the conveyance direction E, under a condition where the sheet 101 a is nipped by the conveyance roller 40 (or sandwiched by a pair of rollers), the continuous sheet 101 a, which has been fed to the conveyance path from the rolled sheet 101, is wound around the roll sheet holder 10. In correspondence with such a motion of the sheet, the tension roller part 20, which is at the first position and contacts to the sheet, is moved upward (or toward the second position). When the tension roller part 20 is detected by the upper sensor 31, it is shut down to energize the solenoid 119 so that the tension roller part 20 is held at the second position (in a lock state).

As shown in FIG. 4C, when the tension roller part 20 is in the second position, the continuous sheet 101 a at a contact portion where the continuous sheet ss in contact with the roller 25 between the transport roller 40 and the roll sheet holder 10 has a second bending angle θ2. The bending angle of the continuous sheet 101 a is defined as an angle formed by a straight portion of the continuous sheet 101 a on the upstream side of the roller 25 (or a portion in which the cross-sectional shape in FIG. 1 and FIG. 4C is linear) and another straight line portion of the continuous sheet on the downstream side of the roller 25 (a portion in which the cross-sectional shape in FIG. 1 and FIG. 4C is linear). The second bending angle θ2 is larger than the first bending angle θ 1. The second bending angle θ2 is desirably in the range of 150° to 180°. More desirably, the second bending angle θ2 is preferably in the range of 170° to 180°.

By maintaining the second bending angle θ2 close to 180°, the continuous sheet 101 a is held in a substantially horizontal state (or no curved state), it is possible to prevent the curling habit from being put of the roll sheet 101 while non-printing period (sheet feeding period). It is noted that the second bending angle θ2 becomes larger as the remaining amount of the rolled paper 101 becomes smaller and the sheet feeding spot (DP) of the continuous sheet 101 a (or where a fed sheet departs from the remaining roller sheet) approaches the roll core 102. The second bending angle θ2 is eventually close to 180°.

In order to achieve the above range of the corner angle, the second position of the roller 25 may be on or closer to a connecting line that connects the conveyance roller 40 and a rotational shaft of the holder 10 than the first position. Also, when the first position is located on one side with respect to the connecting line. The second position may be located on the other side with respect to the connecting line.

As the roll sheet is conveyed to the conveyance path, the roll diameter of the roll sheet decreases. In the embodiment, the second bending angle θ2 is designed to be equal to or less than 180° at any time of the sheet conveyance.

FIG. 5A to FIG. 5C are diagrams for explaining the operations of the roll sheet supply device 100 according to the embodiment, showing the operations following the operations shown in FIG. 4A to FIG. 4C. It is noted that the description of the printing device 200 is omitted in FIG. 5A to FIG. 5C.

As shown in FIG. 5A, when the print data is received from an upper host (e.g., a computer (not shown)) by the printing device 200, the solenoid 119 provided in the tension roller support shaft 21 is electrically powered, the lock is released, and the tension roller part 20 is released so as to be able to rotate up and down. Then, in order to move the tension roller part 20 to the lowest position (first position) at the printing time, the roll sheet holder 10 connected to the holder drive motor 117 is rotated in the roll sheet feeding direction, and the continuous sheet 101 a is fed from the roll sheet 101.

As shown in FIG. 5B, when the lower sensor 32 detects the lowest position of the tension roller part 20, the electrical power for the solenoid 119 provided in the tension roller support shaft 21 is shut down, and becoming the lock state. The tension roller part 20 is held at the position at the printing, which is the lowest position.

As shown in FIG. 5C, for performing to wind the slack of the continuous sheet 101 a, while monitoring the detection information from the holder rotation sensor 35, the roll sheet holder 10 which is connected to the holder drive motor 117 rotates in the back feed direction again, and winds up the continuous sheet 101 a.

FIG. 6 to FIG. 8 are flowchart showing a series of operations of the roll sheet supply device 100 according to the embodiment. FIG. 7 shows sequential steps following step S10 in FIG. 6, and FIG. 8 shows sequential steps following step S21 in FIG. 8. Hereinafter, the operation of the roll sheet supply device 100 according to the embodiment will be described from a condition where the operator sets the continuous sheet 101 a.

As shown in FIG. 6, in step S1, the operator pulls the continuous sheet 101 a from the roll sheet 101, passed the sheet under the tension roller part 20, and set the sheet to the conveyance roller 40 (see FIG. 3A).

Next, in the process of step S2, the sheet sensor 33 detects a presence of sheet, and, when the lower sensor 32 detects the lowest position (YES in step S2), it proceeds to step S3, the energization of the solenoid 119 (or electrically powering the solenoid) provided in the tension roller support shaft 21 is cut off and locked so that the tension roller part 20 is held at a position at the printing time, which is the lowest position.

Next, it proceeds to step S4, the roll sheet holder 10 which is connected to the holder drive motor 117 rotates to convey the continuous sheet 101 a. Then, in the process of step S5, when the sheet end sensor 34 detects the presence (or existence) of sheet (YES in step S5), it proceeds to step S6. In the step, the continuous sheet 101 a is conveyed by a predetermined distance and it stops driving rotation of the holder drive motor 117 (see FIG. 3B).

Then, it proceeds to step S7, as a tension is applied by the tension roller part 20 against the continuous sheet 101 a that is drawn too largely by the operator while setting the continuous sheet 101 a, while monitoring the detection information from the holder rotation sensor 35, the roll sheet holder 10 which is connected to the holder drive motor 117 is rotated in the backward feed direction, and the winding of the continuous sheet 101 a is performed (see FIG. 3C).

Next, in the process of step S8, when the output state of the holder rotation sensor 35 (detection information) becomes stable (YES in step S8), and it proceeds to step S9. The continuous sheet 101 a is determined as fully wound and the rotation of the holder drive motor 117 stops. At this time, a tension by the tension roller part 20 is applied to the continuous sheet 101 a, the tension is applied to the continuous sheet 101 a that is positioned between the conveyance roller 40 and the roll sheet holder 10 (FIG. 4A).

Then, it proceeds to step S10, and waits until the print data is received from an upper host (or upper host device) within a predetermined t period. When the print data within the predetermined period is received (YES in step S10), it proceeds to step S11, performing printing by conveying the continuous sheet 101 a to the printing device 200. In this embodiment, it starts to count the predetermined period at a timing when the rotation of the holder drive motor 117 stops (or conveyance part stops to convey the medium).

At the printing time, by rotating the roll sheet holder 10 which is connected to the holder drive motor 117 in the back feed direction, unnecessary feeding of the continuous sheet 101 a is prevented, which is caused by the conveying of the conveyance roller 40, the supply roller 60, and a conveying mechanism inside the printing device 200. When the printing is finished, the holder drive motor stops driving (see FIG. 4B).

When the print data is not received within the preset period (NO in step S10), it proceeds to step S12 in FIG. 7. In the step, an energization of the solenoid 119 provided in the tension roller support shaft 21 is performed and the tension roller support shaft 21 is unlocked and the tension roller 20 is released to rotate the tension roller part 20 up and down.

Then, it proceeds to step S13. In order to move the tension roller part 20 at the highest position, which is a retracted position during non-printing (second position), while detection information from the holder rotation sensor 35 and the highest position detection information of the upper sensor 31, the roll sheet holder 10 which is connected to the holder drive motor 117 is rotated in the back feed direction, winding the continuous sheet 101 a.

At this time, the roll sheet holder 10 connected to the holder drive motor 117 is rotated in the back feed direction until the upper sensor 31 detects the highest position. The driving force for moving the tension roller part 20 in the upward direction is a tension of the continuous sheet 101 a which is meshed with the conveyance roller 40 and is wound and conveyed with the holder drive motor 117.

Next, in the process in step S14, when the upper sensor 31 detects the highest position (YES in step S14), it proceeds to step S15. The energization of the solenoid 119 provided in the tension roller support shaft 21 is shut down, and locked. The tension roller part 20 is held at the highest position that is the retracted position during non-printing.

Then, it proceeds to step S16, the output state of the holder rotation sensor 35 is monitored to make sure if the output state of the holder rotation sensor 35 is constantly changing. When the output state of the holder rotation sensor 35 is stable (YES in step S16), and it proceeds to step S18. It determines that the continuous sheet 101 a is wound, and stops the rotation of the holder drive motor 117. At this time, the continuous sheet 101 a between the conveyance roller 40 and the roll sheet holder 10 is held in a substantially horizontal state with respect to the tension roller part 20 and in a state where a tension is applied (see FIG. 4C).

When the output state of the holder rotation sensor 35 is constantly changing (NO in step S16), it determines that the continuous sheet 101 a is still being wound. it continues the rotation of the holder drive motor 117 (step S17).

Next, in the processing in step S19, it waits until the print data is received from the upper host (upper host device). When the print data from the upper host is received (YES in step S19), it proceeds to step S20. The solenoid 119 provided in the tension roller support shaft 21 is energized, and unlocked to rotate the tension roller part 20 up and down.

Next, it proceeds to step S21, in order to move the tension roller part 20 to the lowermost position at the printing time, while monitoring the lowest position detection information of the lower sensor 32, it causes the holder drive motor 117 to rotate in the feeding direction of the continuous sheet 101 a, and performs the feeding of the continuous sheet 101 a.

Next, in the processing in step S22, it keeps rotating the holder drive motor 117 until the lower sensor 32 detects the lowest position. The driving force for moving the tension roller part 20 in the downward direction is a tension of the continuous sheet 101 a which is meshed with the conveyance roller 40 and is fed and conveyed by the holder drive motor 117 (see FIG. 5A).

When the lower sensor 32 detects the lowest position (YES in step S22), it proceeds to step S23 in FIG. 8. The energization of the solenoid 119 provided in the tension roller support shaft 21 is shut down and it is locked. The tension roller part 20 is held in a position during printing, which is the lowest position (see FIG. 5B).

Next, in the process of step S24, in order to perform to wind up the slack of the continuous sheet 101 a, while monitoring the detection information from the holder rotation sensor 35, the roll sheet holder 10 which is connected to the holder drive motor 117 again rotate in the back feed direction, and to wind the continuous sheet 101 a (see FIG. 5C).

Next, in the process of step S25, it monitors the output state of the holder rotation sensor 35 (detection information) to determine if the output state of the holder rotation sensor 35 is constantly changing. When the output state of the holder rotation sensor 35 is stable (YES in step S25), it proceeds to step S26, determines that the continuous sheet 101 a is wound, and stops the rotation of the holder drive motor 117.

Next, in the process of step S27, the printing device 200 which received the supply of the continuous sheet 101 a from the roll sheet supply device 100 performs printing on the continuous sheet 101 a. After the printing operation is completed, it proceeds to step S10 in FIG. 6, and performs the process of step S10.

<<3>> Effects

As described above, with the roll sheet supply device 100 according to the embodiment, when print data is not received within a preset waiting period from the upper host, as shown in FIG. 1, the tension roller part 20 which is held in the lowest position is unlocked. As shown in FIG. 4C, the tension roller part 20 is moved to the highest position that is a retracted position such that the continuous sheet the 101 a is held in a substantially horizontal state with respect to the conveyance path and in a state state where a tension is applied to the continuous sheet. Thus, during the supply stop period for which the continuous sheet 101 a is not conveyed, it is possible to prevent the tension roller part 20 from putting the curved habit (or wrinkle) affecting the conveying efficiency on the continuous sheet 101 a.

With the roll sheet supply device 100 according to the embodiment, the solenoid 119 provided in the tension roller support shaft 21 is configured to hold the position of the tension roller part 20 when the electric power is shut down (or deenergized). Even when the apparatus entirely turns off, the tension roller part 20 does not fall, holding the position. Therefore, when the power to the entire apparatus is turned OFF, it can also continue the effect of preventing the curved habit of the continuous sheet 101 a.

Also, based on conventional device in which a tension is always applied to a roll sheet which is fed between a roll sheet support part and a roller by a tension mechanism such as the tension roller or the like, and the conveyance accuracy of the roll sheet is improved by using friction against the tension mechanism, because the tension roller is moved to a releasing position during non-printing period, and a necessary tension is not provided to the paper roll, which is fed between the roll sheet support part and the roller, resulting that the roll sheet is kept in a curved state. Therefore, as the transport interruption time (non-printing period) is longer, the roll sheet is curved more large amount, adversely affecting on the conveyance accuracy of the roll sheet after the conveyance restarts. In contrast, according to the roll sheet supply device 100 of the embodiment, the continuous sheet 101 a is held in a substantially straight state (or horizontal to the conveyance path) during a period of which the conveyance sheet 101 a is not conveyed, preventing to put the curved habit (curl) to the sheet. In the case where there is conveyance suspension, it can also prevent the conveyance accuracy of the roll sheet 101 from being deteriorated after the conveyance restarts.

In the invention, the first corner angle (θ1) is formed when the tension member (or contact portion 25) is in the first position. The second corner angle (θ2) is formed when the tension member (or contact portion 25) is in the second position. Regardless of its position, these corner angles are defined by two tangent lines. The first tangent line is formed at an upstream contact point where the medium comes in contact with the contact portion 25 first after fed from the rolled sheet. In FIGS. 9A and 9B, the points are denoted with UCP. The second tangent line is formed at a downstream contact point where the medium, which runs along the outer peripheral of the contact portion as being curved, departs from the outer peripheral to move to the conveyance part. The points are denoted with DCP.

DESCRIPTION OF REFERENCES

-   10 roll sheet holder, -   20 a tension roller section (tension member), -   21 a tension roller support shaft, -   22 bars, -   23 bars, -   24 spring, -   25 roller (contact portion), -   31 upper sensor, -   32 lower sensor, -   33 sheet sensor, -   34 sheet end sensor, -   35 holder rotation sensor, -   40 conveyance roller, -   50 cutter unit, -   60 supply roller, -   100 roll sheet supply device, -   101 roll sheet, -   101 a continuous sheet, -   102 roll core, -   107 control unit, -   108 CPU, -   109 CPU bus, -   110 RAM, -   111 ROM, -   112 IO ports, -   113 holder drive motor driver, -   114 roller drive motor driver, -   115 solenoid drive driver, -   116 cutter unit driver, -   117 holder drive motor (drive unit), -   118 roller drive motor, -   119 a solenoid, -   120 interface circuit, -   121 interface cable, -   200 printing device, -   201 printing unit 

What is claimed is:
 1. A medium supply apparatus, comprising: a holder that is configured to rotatably support a medium, which is wound in a rolled shape and to be rotated by a drive part, a conveyance part that conveys the medium in a conveyance direction, and is disposed in a downstream side with respect to the holder in the conveyance direction, a tension member that is disposed between the holder and the conveyance part, and contacts to the medium, which is positioned between the holder and the conveyance part, to apply a tension to the medium, a state switching part that has a detection sensor that detects a position of the tension member and switches states of the tension member between two states in correspondence with a detection result by the detection sensor, one state being a fixed state where the tension member is locked such that the tension member is not movable, and the other state being releasing state where the tension members is not locked such that the tension member is movable, a control unit that controls the drive part for the holder, conveyance part, and the state switching part, wherein the tension member is swingable between a first position at which a first corner angle (θ1) is formed and a second position at which a second corner angle (θ2) is formed, the first and second corner angles being determined with two tangent lines formed on the tension member which are seen from a rotational axis view of the holder, one tangent line being at an upstream contact point (UCP) where the medium comes in first contact with the tension member, and the other tangent line being at a downstream contact point (DCP) where the medium, which curves around an outer peripheral of the tension member, departs from the outer peripheral of the tension member, the second corner angle (θ2) being greater than the first corner angle (θ1), the control unit causes the state switching part to switch the state of the tension member to the fixed state in the first position when the medium is supplied, and the control unit causes the state switching part to switch the state of the tension member to the releasing state in the first position when the control unit does not receive an image forming start signal, which is a signal to start an image forming process, for a predetermined period after the conveyance part stops conveying the medium so that the tension medium is moved to the second position as the drive part drives the holder to rotate in an opposite direction to the conveyance direction, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the second position.
 2. The medium supply apparatus according to claim 1, wherein the control unit causes the state switching part to switch the state of the tension member to the releasing state in the second position when the control unit does not receive the image forming start signal, which is the signal to start an image forming process, for another predetermined period after the conveyance part stops conveying the medium.
 3. The medium supply apparatus according to claim 1, wherein a conveyance length of the medium that is determined between the holder and the conveyance part through the tension member when the tension member is at the first position is longer than another conveyance length of the medium when the tension member is at the second position.
 4. The medium supply apparatus according to claim 3, wherein the second position of the tension member is determined to cause the conveyance length to be the shortest.
 5. The medium supply apparatus according to claim 1, wherein the second corner angle ranges from 150° to 180°.
 6. The medium supply apparatus according to claim 1, wherein the second corner angle ranges from 170° to 180°.
 7. The medium supply apparatus according to claim 1, wherein the drive part conveys the medium in the conveyance direction by rotating the rolled medium in a first direction, and the drive part winds up the medium, which was once supplied, around the holder by rotating the rolled medium in a second direction that is opposite to the first direction.
 8. The medium supply apparatus according to claim 7, wherein the drive part moves the tension member from the second position to the first position by rotating the medium in the first direction, and the drive part moves the tension member, which is in the releasing state, from the first position to the second position by rotating the medium in the second direction.
 9. The medium supply apparatus according to claim 1, further comprising: a first position sensor that detects the first position of the tension member, and a second position sensor that detects the second position of the tension member, wherein when the first position sensor detects the first position, the control unit causes the state switching part to switch the state of the tension member from the releasing state to the fixed state, when the second position sensor detects the second position, the control unit causes the state switching part to switch the state of the tension member from the releasing state to the fixed state.
 10. The medium supply apparatus according to claim 1, wherein the conveyance part is configured with a pair of rollers sandwiching the medium.
 11. The medium supply apparatus according to claim 1, wherein the tension member includes a contact portion that contacts to the medium, a supporting member that supports the contact part and a supporting shaft that is provided in an apparatus body and rotatably supports the supporting member, and the contact portion swings between the first position and the second position by the supporting member rotating around the support shaft.
 12. The medium supply apparatus according to claim 11, wherein the contact portion includes a roller that is rotatably disposed at a tip of the support member.
 13. A medium supply apparatus, comprising: a holder that is configured to rotatably support a medium, which is wound in a rolled shape and to be rotated by a drive part, a conveyance part that conveys the medium in a conveyance direction, and is disposed in a downstream side with respect to the holder in the conveyance direction, a medium guide part that has a curved portion, is disposed in a upstream side with the conveyance part in the conveyance direction, a tension member that is disposed between the holder and the medium guide part along the conveyance path and applies a tension to the medium by contacting, the tension member being swingable between a first position and a second position, when the tension member is at the first position, the medium being curved by the curved portion of the medium guide part so that the medium is in a curved shape, seen from a side view of the medium being conveyed, the side view being perpendicular to the conveyance direction and to flat surfaces of the medium, when the tension member is at the second position, the medium not contacting to the curved portion of the medium guide part so that the medium is in a linear shape, seen from the side view of the medium, the tension applied by the tension member being oriented from the second position to the first position, a state switching part that has a detection sensor that detects a position of the tension member and switches states of the tension member between two states in correspondence with a detection result by the detection sensor, one state being a fixed state where the tension member is locked such that the tension member is not movable, and the other state being releasing state where the tension members is not locked such that the tension member is movable, a control unit that controls the drive part for the holder, conveyance part, and the state switching part, wherein the control unit causes the state switching part to switch the state of the tension member to the fixed state in the first position when the medium is conveyed to the downstream side for an image forming process, and the control unit causes the state switching part to switch the state of the tension member to the releasing state in the first position when the control unit does not receive print data for the image forming process for a predetermined period after the conveyance part stops conveying the medium so that the tension medium is moved to the second position as the drive part drives the holder to rotate in an opposite direction to the conveyance direction, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the second position.
 14. The medium supply apparatus according to claim 13, wherein the tension member is configured to be biased by a spring, which consistently pushes the tension member toward the first position, when the state switching part switches the state of the tension member, which is in the second position, from the fixed state to the releasing state, the tension member is moved toward the first position due to the spring, and the control unit causes the state switching part to switch the state of the tension member to the fixed state when the tension member reaches the first position. 